Saturn

NASA and JPL released this image of a 400 kilometer long river system on Titan. The image was taken on 26 September 2012 by the Cassini spacecraft (in orbit around Saturn) during its 87th flyby of Titan.

The image is oriented with North to the right. The river system flows into the Ligeia Mare, one of three oceans in the northern hemisphere of Titan.

The river is black in appearance, which denotes a smooth surface. Therefore, scientists think that the river is filled with liquid Methane and Ethane along its entire distance.

Plumes of water and other gases from Enceladus, one of Saturn’s large moons, is now thought to be the source of the dusty plasma circling Saturn. The gases react with the magnetic field of Saturn, stripping electrons from the atoms and molecules. In addition, nano-particles are formed mixed in the plasma. The new results (“Charged nanograins in the Enceladus plume“) have been published in this month’s Journal of Geophysical Research Space Physics:

There have been three Cassini encounters with the south-pole eruptive plume of Enceladus for which the Cassini Plasma Spectrometer (CAPS) had viewing in the spacecraft ram direction. In each case, CAPS detected a cold dense population of heavy charged particles having mass-to-charge (m/q) ratios up to the maximum detectable by CAPS (∼104 amu/e). These particles are interpreted as singly charged nanometer-sized water-ice grains. Although they are detected with both negative and positive net charges, the former greatly outnumber the latter, at least in the m/q range accessible to CAPS. On the most distant available encounter (E3, March 2008) we derive a net (negative) charge density of up to ∼2600 e/cm3 for nanograins, far exceeding the ambient plasma number density, but less than the net (positive) charge density inferred from the RPWS Langmuir probe data during the same plume encounter. Comparison of the CAPS data from the three available encounters is consistent with the idea that the nanograins leave the surface vents largely uncharged, but become increasingly negatively charged by plasma electron impact as they move farther from the satellite. These nanograins provide a potentially potent source of magnetospheric plasma and E-ring material.

Cassini has imaged small objects puncturing the F-ring of Saturn, leaving behind trails of debris that scientists have termed ‘mini-jets’.

Having chanced upon this phenomenon, Carl Murray, a Cassini imaging team member based at Queen Mary University of London, England and others searched through 20,000 images during the seven years Cassini has been at Saturn, and culled some 500 that show these wispy streaks.

Now the imaging team thinks they have the story. Prometheus is a large object in the dynamic F-ring, and its long axis is almost 150 kilometers. It is known to create channels, ripples and snowballs in the F ring, as shown in this video collage. Although a lot of the debris from these collisions dissipate, some of the 1 kilometer sized snowballs persist. They occupy orbits that take them above and below the F-ring, and collide with other particles in the ring at slow relative speeds, around 2 meters per second. These collisions drag glittering ice particles out of the ring, creating the 50 to 150 kilometer long ‘mini-jets’.

The spacecraft Cassini will make a second pass today through the jets spraying from the south pole of Enceladus, one of Saturn’s moons. Less than three weeks ago, Cassini made a similar pass through the jets (27 March). Combined with a previous pass on 1 October, these three passes should allow the ion and neutral mass spectrometer to determine the three dimensional structure of the jets and how they change over time.

This flyby will occur at an altitude of 74 kilometers (46 miles), the same as the March flyby. The plumes are composed of jets of water ice and vapor, and organic compounds emanating from the south polar region. Other measurements of the plumes include the plasma spectrometer and composite infrared spectrometer.

Currently, the storm is 10,000 kilometers wide and 17,000 kilometers long, with a tail extending 100,000 kilometers. The storm was imaged on 5 December 2010 when it was a small white spot. This image was taken on 24 December 2011.

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Next Meeting (All Speaker Meetings are Free and Open to the Public)

November 1oth: Movie Night,

Mike is inviting all his spacey friends to a movie night at his home in Gilbert next Saturday evening, November 10. We’ll watch the 2017 movie “Salyut 7”, a pseudo-documentary about the resuscitation of the Soviet space station. It’s a two-hour movie, so we’ll kick it off around 7:30 pm. Mikes lives near US60 and Stapley, and please contact him if you plan to attend. Should be a fun evening.

November: Out reach at Library Con. is Cancelled. Library Con will not be hosting an event this year.

November: VR for good service opportunity, cancelled due to sufficient staff was already obtained.

if you would like request for an opportunity to teach a topic about space at our monthly meeting or Have an Idea about an NSS Outing we can do. please email Phyllis.Redhair2012@gmail.com